The bearings being inside the wheels is actually no biggy; if you were running a fleet of hundreds of these locomotives, you'd just lay in a stock of replacement wheelsets, the same as the railroads do now-a-days for freight cars. When a bearing commits suicide, they just throw the whole wheelset away. But Kelly's point is well taken; if you have a unique wheelset that no one can replace on the road, maybe bearings that can be doctored make more sense.

_________________Dennis Storzek

TrainDetainer

Post subject: Re: U.S. Sugar / F.E.C. #148 restoration progress

Posted: Fri Feb 09, 2018 7:01 pm

Joined: Wed Nov 23, 2016 7:05 pmPosts: 81

Quote:

For my locomotive, I would never convert them to rollers in that in my opinion plain bearings are superior to roller bearings in that the truck will be more flexible with plain bearings

Kelly -

I have to agree that a solid split box like you did for these two instances has to be far more rigid than a plain bearing under a wedge - Any thought to hogging out the box and putting a radius in the pedestal grooves so that the boxes can function more like a standard narrow RB adapter? Something like the white areas here -

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Or is there some extra slop that we can't see built in? The r6 tolerance for 140-200mm locomotive bearings (looks like about a 6" axle to me) in Timken's design pages doesn't leave a whole lot of slop, but there is a little. I realize there isn't much room in a lot of engine/pony truck boxes for full conversions, but in the case of 148 there looks to be enough room to put a standard adapter that would give almost the same flexibility as a car truck.

The other thing that makes my curiosity meter bounce around is the heat dissipating ability of a solid block surrounding the entire bearing. Timken's bearing paper work includes the general statement that every 10 degree C increase in temp shortens lube life by half, but they don't go very far into heat removal and say nothing in what I saw about AP/AP-2 assemblies as a whole. From the relatively few RB hot boxes I've encountered, radiant air cooling seems to be a fairly important factor. Any thoughts?

That said, those are great looking spoked centers and always nice to see Strasburg's work. I take it the pedestals are new fab to accommodate the new boxes too?

_________________G.______________________________________Radio crackles - "What the #^(& did we just hit, over?"

Kelly - Thanks for the additional information and for giving your take on whether the conversion was advisable.

Kelly Anderson

Post subject: Re: U.S. Sugar / F.E.C. #148 restoration progress

Posted: Sat Feb 10, 2018 9:57 am

Joined: Tue Sep 14, 2004 7:52 amPosts: 1287Location: Strasburg, PA

TrainDetainer wrote:

I have to agree that a solid split box like you did for these two instances has to be far more rigid than a plain bearing under a wedge Lead truck plain bearings don't use wedges, the brass is directly in touch with the box. - Any thought to hogging out the box and putting a radius in the pedestal grooves Already done. so that the boxes can function more like a standard narrow RB adapter? Something like the white areas here -The bearing fit in the box is based on the common design used in converting old oil lubricated passenger car roller bearings to AP bearings, where a steel tube is installed in the box and bored out to take an AP bearing.

Or is there some extra slop that we can't see built in? The r6 tolerance for 140-200mm locomotive bearings (looks like about a 6" axle to me) in Timken's design pages doesn't leave a whole lot of slop, but there is a little. I realize there isn't much room in a lot of engine/pony truck boxes for full conversions, but in the case of 148 there looks to be enough room to put a standard adapter that would give almost the same flexibility as a car truck.

The other thing that makes my curiosity meter bounce around is the heat dissipating ability of a solid block surrounding the entire bearing. Timken's bearing paper work includes the general statement that every 10 degree C increase in temp shortens lube life by half, but they don't go very far into heat removal and say nothing in what I saw about AP/AP-2 assemblies as a whole. From the relatively few RB hot boxes I've encountered, radiant air cooling seems to be a fairly important factor. Any thoughts? Again, this situation is equivalent to most private cars bearing conversions out there.

That said, those are great looking spoked centers and always nice to see Strasburg's work. I take it the pedestals are new fab to accommodate the new boxes too? The truck came to us with those fabricated pedestals.

My point about flexibility has to do with the ability of a plain bearing wheel set to be free to slide from side to side within its lateral limits (5/16" new for our #90) as easily as it rotates. These boxes are as free in the pedestals as the originals, and the bearings have some lateral slop built in before they reach their shoulder in the boxes (1/8", the same as the slop to a bearing adaptor), but it is a dry, steel on steel fit, not nearly as free to adjust itself to moment to moment adaptations as the engine goes down the track.

_________________"It was not easy to convince Allnutt. All his shop training had given him a profound prejudice against inexact work, experimental work, hit-or-miss work."C. S. Forester

My point about flexibility has to do with the ability of a plain bearing wheel set to be free to slide from side to side within its lateral limits (5/16" new for our #90) as easily as it rotates. These boxes are as free in the pedestals as the originals, and the bearings have some lateral slop built in before they reach their shoulder in the boxes (1/8", the same as the slop to a bearing adaptor), but it is a dry, steel on steel fit, not nearly as free to adjust itself to moment to moment adaptations as the engine goes down the track.

This means that the normal free float built into the engine truck is not there and the centering device must deal with all lateral movement. This may not be a bad thing from a stable tracking standpoint but will result in some (perhaps slight) additional wear on the wheel flanges and centering mechanism. Any thoughts on how to address this or is it considered insignificant?

I would not think that the AP bearings normally see these lateral loads in a regular car truck. Does this appear to appreciably shorten their life in this type of service?

Kelly Anderson

Post subject: Re: U.S. Sugar / F.E.C. #148 restoration progress

Posted: Sat Feb 10, 2018 11:35 am

Joined: Tue Sep 14, 2004 7:52 amPosts: 1287Location: Strasburg, PA

Russ Fischer wrote:

I would not think that the AP bearings normally see these lateral loads in a regular car truck.

I would bet the the car in front of a two unit pusher going around curves sure would!

The catalog says that a 5x9 is good for 10,000 lb of thrust at 500 RPM for 3,000 hours, for what that's worth.

I would say that in this kind of service, they should have a normal service life, backed up by the positive experiences that other locomotives have had with this conversion.

On the other hand, when GSMRy tried AP bearings in driving boxes, they failed in short order. It was detailed in a thread here years ago.

_________________"It was not easy to convince Allnutt. All his shop training had given him a profound prejudice against inexact work, experimental work, hit-or-miss work."C. S. Forester

My point about flexibility has to do with the ability of a plain bearing wheel set to be free to slide from side to side within its lateral limits (5/16" new for our #90) as easily as it rotates. These boxes are as free in the pedestals as the originals, and the bearings have some lateral slop built in before they reach their shoulder in the boxes (1/8", the same as the slop to a bearing adaptor), but it is a dry, steel on steel fit, not nearly as free to adjust itself to moment to moment adaptations as the engine goes down the track.

This means that the normal free float built into the engine truck is not there and the centering device must deal with all lateral movement. This may not be a bad thing from a stable tracking standpoint but will result in some (perhaps slight) additional wear on the wheel flanges and centering mechanism. Any thoughts on how to address this or is it considered insignificant?From J3a-614's search here is a similar experience with car wheel sets. Emphasis added by me:

I would not think that the AP bearings normally see these lateral loads in a regular car truck. Does this appear to appreciably shorten their life in this type of service?

This post mentions that type of problem taking place on converted 6 wheel trucks:

Ryan Scott wrote:

While I was at the Smokys I dealt with the aftermath of many friction to roller conversions. All of the cars were roller, some AP, some not. Almost all of the coach and crown cars were old six axle heavyweights that had either been converted from frictions (or old hyatt/skf rollers) to AP rollers. Some still had the SKF bearings under them. There was a mix of old 5x9 and 5.5x10 trucks, but all the AP bearings were 5.5x10 so you had to watch what your bearing centerlines were on the wheelsets. Some of the boxes were cast adapter boxes for this very purpose, some were home made jobs. There were pros and cons to each.

The conversions worked well, save one issue. The reduction in lateral play was not in the favor for six axle cars working on a mountain railroad. The real problem was that those six axle cars didn't (and do not) belong on a railroad that is operating daily service through 43 miles of 10-15 degree curves. The loss of the lateral made it worse. In order to get enough lateral, you had issues with equalizers rubbing on the pedestals, and all the issues that arise from that. So you remove the lateral and then create high wear rates on the pedestal liners and boxes. At the same time the flange wear was incredible. No joke, I had some cars that came in for wheel replacement every 18 months because the flanges were dead. I had to renew many of the box and pedestal wear plates at the same time. Many times I half considered converting back to frictions just to get the lateral back. Really though, if I had my way we would have replace the daily runners with four axle coaches. I continued to convert some of the four axle cars to AP rollers, from Hyatt, SKF, and Timken lube bearings. Most of that was due to parts availability and to help with commonality of spares. I think I had 12 different types of wheelsets when I started there.

Bottom line, newer isn't always better. It's a matter of what works well for the environment you are in. What is more robust in one application may be a detriment in another. Interesting note that one of the posts in this thread noted rollers on a steam locomotive. I'd lay money that hey was talking about the AP rollers that were on the 1702. Same story. That is why we went back to frictions. They just work better for that application.

Feel free to back channel me if you would like to discuss more. . .

Ryan Scott

The thread I was thinking of doesn't seem to have been saved on Rypn, though I did find it in the Ultimate Steam Page.

Quote:

There were a few "flaws in the slaw", so to say, that led to earlier-than-expected replacement of the roller bearings.

1. The rollers were Timken "AP" bearings. In other words, they were sealed for life with grease. They could not be "flushed" periodically like any other true steam locomotive roller bearing. The ability to change the oil periodically may have helped. Also, the use of oil instead of grease will let some of the loose metal particles collect at the bottom of the bearing box, instead of continuing to grind the remaining bearing just like grinding compound.

2. The rollers were not housed in a common box, as in standard locomotive roller bearing boxes. In roller bearing locos, such as the NKP 765, the left and right boxes on a particular axle were actually all one box. There are two halves to the box, and upper and a lower. Thus, as the box encountered the frame during lateral movement, both bearings were loaded exactly the same, because they were located in a precise machined "common" box. Also, with the common box, the spring rigging cannot induce moments on the bearing in the same axis as the rail. Also, the bearing designs themselves differ from the standard loco bearing to the AP bearings.

3. The AP bearings were designed to be used in two to three axle trucks that had a much smaller wheelbase than a steam locomotive. In this case a 2-8-0 with 57 inch drivers. Also, they were meant for smaller wheels and higher speeds, say 36 inch wheels and 45-60mph. At the higher speeds the AP bearings would heat up enough to evaporate whatever water might pass the seals in weather changes, and in the case of a steam loco, steam cleanings. The AP bearings just couldn't handle the lateral load that a 2-8-0 on a curvy RR will create.

The conversion to Roller bearings on this loco was an experiment. Unfortunately, as with any experiment, we are sometimes disappointed with the data that we are presented with after starting the experiment. Couple that with the fact that AP bearings are meant to last for "life", with "life" being measured in the length of time it takes to wear out the wheel on the same axle. On a steam loco, it is MUCH more involved to remove a roller bearing than on a freight car axle. One must dismount/mount the wheels which over time will "wear" the interference fit between the axle and wheel, and also requarter the crankpins after each of these "lifetime" replacements. Thus, axles and crankpins last much longer with true RR roller bearings or friction bearings.

The #1702 has been converted back to friction bearings on all drive axles for many of the reasons above. For all of those contemplating a roller bearing conversion think long and hard about the costs versus benefits both short and long term.

Ryan Scott

_________________"It was not easy to convince Allnutt. All his shop training had given him a profound prejudice against inexact work, experimental work, hit-or-miss work."C. S. Forester

I've seen advertisements for split roller bearings for marine propeller shafts in 'the yellow paper', Boats and Harbors. I have often thought that these might be suitable for inboard bearing lead and trailing trucks, which would eliminate the need to press off wheels when changing bearings.

One page I just looked at on the web showed bearings available for up to a fourteen inch shaft diameter, so I'm sure sizes that would be useful for rail applications would be available. Or am I missing something here? Lots of marine stuff is applicable to rail, and vice versa.

After several solid bearing problems, we finally converted the pilot truck to roller bearings. We used Amtrak wheelsets/bearings and Doyle MacCormack had boxes cast for us, which we machined. Never had a minute's worth of problem from then on. We also went through the pilot truck again and made sure everything was up to snuff.We went on to convert the trailing truck and tender trucks to rollers.

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